On Tue, 2014-05-13 at 10:00 -0400, Dave Jones wrote:
> On Tue, May 13, 2014 at 04:43:48PM +1000, Michael Ellerman wrote:
>
> > I'm consistently ending up with a watchdog that is spinning using 100% cpu.
> >
> > We are bailing out of __check_main() before clearing shm->mainpid because
> we
> > see that we are already exiting.
> >
> > if (ret == -1) {
> > /* Are we already exiting ? */
> > if (shm->exit_reason != STILL_RUNNING)
> > return FALSE;
> >
> > /* No. Check what happened. */
> > if (errno == ESRCH) {
> >
> >
> > 161 if (shm->exit_reason != STILL_RUNNING)
> > (gdb) print shm->exit_reason
> > $6 = EXIT_FORK_FAILURE
> >
> > It looks like the only other place shm->mainpid is written is in
> > trinity.c:main(), which is dead. So we are stuck forever as far as I can
> tell.
>
> Argh. I hit this exactly once a few weeks back, and thought I had fixed it.
>
> > The last thing in trinity.log is:
> >
> > [main] couldn't create child! (Cannot allocate memory)
> >
> > >From main.c:69:
> >
> > output(0, "couldn't create child! (%s)\n", strerror(errn o));
> > shm->exit_reason = EXIT_FORK_FAILURE;
> > exit(EXIT_FAILURE);
> >
> >
> > So we exited directly and didn't let the code in main() clear shm->mainpid.
> >
> > Not sure what the correct fix is.
>
> I think just clearing mainpid before we call exit is the right thing to
> do here. I'll audit all the other exit() calls too, as this might be a
> problem in other paths.
Thanks. That fix is working for me.
It still exits after a minute or so, because it fails to fork a child in
fork_children().
I have 64 cpus and 16GB of RAM, so that's only 250MB per child.
If I reduce to 32 children then it runs much longer.
I wonder though, should failing to fork a child be a fatal error? Or could it
just skip that child and continue.
cheers
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